/*
 * Metadata - jQuery plugin for parsing metadata from elements
 *
 * Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
 *
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
 *
 * Revision: $Id: jquery.metadata.js 3640 2007-10-11 18:34:38Z pmclanahan $
 *
 */

/**
 * Sets the type of metadata to use. Metadata is encoded in JSON, and each property
 * in the JSON will become a property of the element itself.
 *
 * There are four supported types of metadata storage:
 *
 *   attr:  Inside an attribute. The name parameter indicates *which* attribute.
 *
 *   class: Inside the class attribute, wrapped in curly braces: { }
 *
 *   elem:  Inside a child element (e.g. a script tag). The
 *          name parameter indicates *which* element.
 *   html5: Values are stored in data-* attributes.
 *
 * The metadata for an element is loaded the first time the element is accessed via jQuery.
 *
 * As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
 * matched by expr, then redefine the metadata type and run another $(expr) for other elements.
 *
 * @name $.metadata.setType
 *
 * @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
 * @before $.metadata.setType("class")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from the class attribute
 *
 * @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
 * @before $.metadata.setType("attr", "data")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a "data" attribute
 *
 * @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
 * @before $.metadata.setType("elem", "script")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a nested script element
 *
 * @example <p id="one" class="some_class" data-item_id="1" data-item_label="Label">This is a p</p>
 * @before $.metadata.setType("html5")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a series of data-* attributes
 *
 * @param String type The encoding type
 * @param String name The name of the attribute to be used to get metadata (optional)
 * @cat Plugins/Metadata
 * @descr Sets the type of encoding to be used when loading metadata for the first time
 * @type undefined
 * @see metadata()
 */

(function ($) {

  $.extend({
    metadata: {
      defaults: {
        type: 'class',
        name: 'metadata',
        cre: /({.*})/,
        single: 'metadata'
      },
      setType: function (type, name) {
        this.defaults.type = type;
        this.defaults.name = name;
      },
      get: function (elem, opts) {
        var settings = $.extend({}, this.defaults, opts);
        // check for empty string in single property
        if (!settings.single.length) settings.single = 'metadata';

        var data = $.data(elem, settings.single);
        // returned cached data if it already exists
        if (data) return data;

        data = "{}";

        var getData = function (data) {
          if (typeof data != "string") return data;

          if (data.indexOf('{') < 0) {
            data = eval("(" + data + ")");
          }
        };

        var getObject = function (data) {
          if (typeof data != "string") return data;

          data = eval("(" + data + ")");
          return data;
        };

        if (settings.type == "html5") {
          var object = {};
          $(elem.attributes).each(function () {
            var name = this.nodeName;
            if (name.match(/^data-/)) name = name.replace(/^data-/, '');
            else return true;
            object[name] = getObject(this.nodeValue);
          });
        } else {
          if (settings.type == "class") {
            var m = settings.cre.exec(elem.className);
            if (m)
              data = m[1];
          } else if (settings.type == "elem") {
            if (!elem.getElementsByTagName) return;
            var e = elem.getElementsByTagName(settings.name);
            if (e.length)
              data = $.trim(e[0].innerHTML);
          } else if (elem.getAttribute != undefined) {
            var attr = elem.getAttribute(settings.name);
            if (attr)
              data = attr;
          }
          object = getObject(data.indexOf("{") < 0 ? "{" + data + "}" : data);
        }

        $.data(elem, settings.single, object);
        return object;
      }
    }
  });

  /**
   * Returns the metadata object for the first member of the jQuery object.
   *
   * @name metadata
   * @descr Returns element's metadata object
   * @param Object opts An object contianing settings to override the defaults
   * @type jQuery
   * @cat Plugins/Metadata
   */
  $.fn.metadata = function (opts) {
    return $.metadata.get(this[0], opts);
  };

})(jQuery);